Calcium carbonate minerals are spread throughout the world, which is why they have been among the most widely used raw materials for more than 5000 years. Although the deposits are plentiful, only a few are of sufficiently high quality to be worked and even a fewer number of deposits will provide raw materials for industrial and agricultural uses other than the construction and roads building industry. After quarrying, further treatment is required to process natural calcium carbonates of the highest quality, known generically as Ground Calcium Carbonate (GCC). Precipitated Calcium Carbonate (PCC) is a synthetic calcium carbonate produced industrially by means of a recarbonisation process. Both GCC and PCC can be used in a wide range of applications. For each end use there exists a tailor-made product, where fineness and particle size distribution are optimally balanced to meet the technical demands of that particular requirement.
Over the last 30 years, the use of calcium carbonate has grown significantly as technology in the paper industry has moved from acid to neutral sizing. Today, calcium carbonate is the most widely used mineral in papermaking. GCC and PCC are used both as a filler and a coating pigment, and help produce papers with high whiteness and gloss and good printing properties. Other uses of calcium carbonates include: a filler for breathable polyethylene films, the main extender for paints and coatings, a source of calcium in fertilizers, and a component in glass, ceramics, chalk, and dental care and cosmetic products.
Peptides having a binding affinity to polymer and semiconductor surfaces are known. For example, Adey et al., (Gene 156:27-31 (1995)) describe peptides that bind to polystyrene and polyvinyl chloride surfaces. Peptides that bind to polyurethane (Murray et al., U.S. Patent Application Publication No. 2002/0098524), polyethylene terephthalate (O'Brien et al., co-pending and commonly owned U.S. Patent Application Publication No. 2005/0054752), and polystyrene, polyurethane, polycarbonate, and nylon (Grinstaff et al., U.S. Patent Application Publication No. 2003/0185870) have been reported. Additionally, Whaley et al. (Nature 405:665-668 (2000)) and Belcher (U.S. Patent Application Publication No. 2003/0148380) disclose the use of phage display screening to identify peptide sequences that can bind specifically to different crystallographic forms of inorganic semiconductor substrates. The use of phage display to identify peptides that specifically bind carbon-based nanostructures is described by Jagota et al. (co-pending and commonly owned U.S. patent application Ser. No. 10/453,415; WO 03/102020).
Polyanionic peptides with an affinity for calcium carbonates are known (see for example, DeOlveira et al., J. Amer. Chem. Soc. 119:10627-10631 (1997), and Wheeler et al., Surface Reactive Peptides and Polymers, ACS Symposium Series 444, C. S. Sikes, ed.; American Chemical Society, Washington, D.C., 1991, Chapter 6). However, the use of such peptides to target and modify calcium carbonate surfaces has not been described.
There remains a need therefore for a peptide-based reagent that binds calcium carbonate minerals and offers flexibility in bringing a wide variety of materials to the calcium carbonate surface with minimum investment in redesign. Applicants have addressed the stated problem by providing calcium carbonate-binding peptide (CCBP) reagents comprising at least one calcium carbonate-binding peptide domain (CCBD). The calcium carbonate-binding peptides disclosed herein may further comprise other functional or binding peptide domains allowing for the delivery of benefit agents to the calcium carbonate surface or for the use of the reagents to adhere calcium carbonate-containing surfaces.